Electric timing switch



Oct. 4, 1927..

C. F AMOS ELECTRIC TIMING-SWITCH Flled July 17 1926 Invehl'or:Gil-)Kmo's f I m n Patented Oct. 4, 1927.

rU-"NIT' ED. stares oYnILrnEnnIoKeMos, or ROCHESTER, ENGLAND.

, ELECTRIC TIMING ISWITCH.

V Application filedJuly 17, 1926, Serial No. 123L241,.and in GreatBritain lllayfia, 1926. V

{The invention concerns an electric timing switch, itsobject being toprovide a simple and reliable switch which can be set to con- ,trol anelectric circuit for a predetermined time, and is more particularlysuitable for ,use with electric toasters for the purpose ofswitching-oil the toaster to prevent the toast from being burnt.

With this Object in view, I provide a tim- .ingdevice somewhatsimilar toaclock, one hand of which is insulated and is adapted to be driven bytheclockwork overan arcu ate-contact plate, the current passing therethrough until automatically interrupted by the disengaging oflthe handfrom the plate after a predetermined time. Means are provided forsetting the hand or contact arm) and torretaining it insetposition untilr'eleased .at. the appropriate time, and again for stopping the. arm atselected-points.

The invention will-be more readily understood from the followingdescription with reference to thehaccompanying drawings, wherein: Figure1 is a sectionalelevation showing the preferred ,form of deviceaccordingto theinvention, Figs. 2 and 3 are ,plan views'to .areducedscale indicating alternative arrangements of the contact plate andadjacent parts, Figs. 1 and 5 shows an endandside viewrespectively of anadjustable stopping device to an an enlarged scale, andFigs. 6 and 7 aresimilar views of an alternative stoppingdevice such as is indi cated'inFig. 3.

Reterring more particularly to Fig. 1,.in a-casing 1 isarranged aclockwork mechanismgindicated more or less diagrammatical- 1y,adaptedtobe wound by a key 2 and to drive a spindle 3. On the upper'endof spindle 3 is part lot a -multi-toothed clutch, the co-operating part5 of which is of insulating material, carries a contact arm 6, andterminates in an operating knob 7 passing through the top of casing 1.

An insulating sleeve 8 is journalled concentrically upon the clutchportion 5, one end of said sleeve being adapted to screw into thecontact arm 6, while its other end passes through the top of easing 1and is furnished with a head 9. About the center of sleeve 8 is suitablyprovided a collar 10, between which and the casing is inserted acompression spring 11, while beneath said collar is disposed anelectrical conductor 12 and a resilient spider 13 the extremities ofwhich bear upon the contact arm 6. The end of tact plate 14.

mounted, and isresiliently held in itsraised the c'ontactarniiti isadaptedto moreove an arcuate contactplatedEet, *andit-willbe readilyseen that by turning-the head 9 while the contact arm is'held'stationary,

for example by means ofknob'7,flthe pressure of the contact arm uponthecont-act.

plate 1 1 canbe adjusted.

The contact plate is mounted upon-insulating blocks 15 anddoes not forma complete circle, but is interrupted at thepoint where a releasablestop '16 is'pr'ovided, as is best shown in Fig.2. Thus, when the arm 6is retained by the stop 16,.as1i's shown in the drawings, it isinsulatedtrom the con- The stop 16 is pivotally position, as showninFig. 11. lf the button 17, which projects throughvthe casing l and "isconnected with the stop 16, is pressed in, the stop 16 is moved outofthe-path-ofthe arm 6-and allows thelatter to moveove-r the contactlate, rgedbythe clockwork drive.

.T he conductor '12 and the contact plate 14 are respectively connectedto terminals 18, 19 onthe casing 1,;and inuse the latter are interposedin one of the current supply leads to the toaster, s'o that-thelatterwill onlyoperate solong asthe current passes throughthe contact arm=6and contact plate .14. The operation of the simple form of thedevice-above described is .asfollows:- I V The arm 6 is first. setin:theip-repa r.atory position, if necessary, byraising 'knob .7lt0'disengage the clutch 1-,i5and then turning the knob until arm6 engagesbehindstop 16. Knob i' isthen releasedand the; clockwork is wound to thevfull extent. lVhen ready to commence toasting, buttoir17is; depressedand arm 6{immediatelymoves in a clockwise direction, and current .flowsthrough the toaster-as the arminoves over the contact plate. Theclockwork is so devised that the arm 6 normally takes, say five minutesto move completely over the contact plate. Thus, after a period of five'minutes the toaster is automatically cut off Figs. 3, 6 and 7,insulating pieces are inlaid in the surface of the contact plate todivide same into a number of arcuate portions. A slot 21 is formed inthe top of the casing 1, being provided with recesses 22 above theinsulated portions of the contact plate. A sliding stop 23 is providedin slot 21, said stop having an enlarged portion corresponding in sizeto recesses 22, and a reduced portion corresponding to the narrowerwidth of the slot 21 (vide Figs. 6 and 7). A small spring 24 is carriedby the stop 23, and in use the stop 23 is slid along the slot 21 untilit coincides with a selected recess 22, into which it enters and is thusheld fast. The arm 6 when released will then travel over the contactplate, the current being in terrupted momentarily each time the armpasses over one of the insulating pieces, at

one of which it is finally arrested by the stop 23. i

Another form of adjustable stop is shown in Figs. 4 and 5, and in thisinstance the contact plate 14 maybe continuous, but is of special form,being recessed to form a guide for an insulating wed e piece 25. Thelatter is provided with a clamping screw 26 passing through a slot 27 inthe casing, and can be adjusted and clamped at any desired point of thecontact plate, e. g. over a semicircular arc thereof. The contact arm issuitably shaped at its extremity so that normally it rests upon theupper surface of the contact plate, but on reaching the wedge piece 25it is raised slightly so as to break the contact, and comes to astandstill.

It will be readily seen that the electric timing devices above describedwill be of great convenience in use, and may be variously modifiedwithout departing from the spirit of the invention. For example, the topof the casing may be marked, or even. a dial provided as in a clock, forco-operation with the arm or with the adjusting knobs for the purpose ofshowing, or more accurately predetermining the timing of the device.Further it may be preferred to incor porate the device permanently in anelectric toaster, as will be apparent to those skilled in the artwithout further explanation.

I claim z- 1. An electric timing switch comprising a plate, a clutchdevice interposed between said contact arm and driving means, a clutchoperating member extending through said casing and connected to thecontact arm, releasable stop means tor retaining said arm in setposition until released, an operating button for said stop meansextending through the casing, and means for automatically disengagingsaid contact arm and plate after a predetermined interval.

3. An electric timing switch comprising a casing, 21 contact arm pivotedin said casing, an arcuate contact plate secured in said casing forco-operation with said arm, clockwork means for driving said arm oversaid plate, a clutch device interposed between said contact arm anddriving means, a clutch operating member extending through said casingand connected to the contact arm, means for adjusting the pressurebetween said contact arm and plate, releasable stop means for retainingsaid arm in set position until re leased, an operating button for saidstop means extending through the casing, and means for automaticallydisengaging said contact arm and plate after a predetermined interval.

4. In an electric toaster, a timing switch comprising a pivotal contactarm and an arcuate contact plate for co-operation therewith interposedin the toaster circuit, clockwork means for driving said, arm over saidplate, means for setting said arm, releasable stop means for holdingsaid arm in set position until released, and means for automaticallydisengaging said arm from the contact plate after a predeterminedinterval.

CYRIL FR EDRICK AMO

